Desulfurization of organic substances



Jan. 31, 1950 A. P. LIEN arm.

DESULF'URIZATION OF ORGANIC SUBSTANCES 2 Sheets-Sheet 1 Filed Dec. 27,1946 mm BSQQ Q Jan. 31, 1950 A. P. LIEN ETAL 2,495,851

DESULFURIZATION OF ORGANIC SUBSTANCES Dec. 27, 1946 2 Sheets-Sheet 2kwlnttkm y Patented Jan. 31, 1950 UNITED STATES PATENT OFFICEDESULFURIZATION or ORGANIC SUBSTANCES Arthur P. Lien, Hammond, 1nd,, andBernard L. Evering, Chicago, IlL, assignors to Standard Oil Company,Chicago, 111., a corporation of Indiana Application December 27, 1946,Serial No. 718.855

11 Claims.

vide an improved method of refining petroleum fra tions to separatetherefrom sulfur and undesirable sulfur compounds. A still furtherobject of the invention is to provide an effective method of refininghydrocarbons.

Other objects and advantages of the present invention will becomeapparent from the following description thereof read in conjunction withthe accompanying drawing, which forms a part of the specification and inwhich Figure 1 is a flow diagram of one method of carrying out theinvention;- and Figure 2 is a flow diagram of a, modified method ofcarrying out the invention.

In accordance with the present invention, sulfur-bearing organicmaterials, such as hydrocarbon compounds, for example hydrocarbon oils,such as petroleum oils and petroleum fractions are effectively freed ofsulfur and sulfur compounds by extracting such materials with a solventcomprising essentially boron fluoride and a com lex of boron fluoridewith an oxygenated organic compound or halogen, preferably chlorine,derivatives of such oxygenated organic compounds which can be employedwhen forming the boron fluoride complexes are the following:

Methyl ether Methyl formate Ethyl ether Ethyl formate Propyl ether Butylformate Butyi ether Ethyl propionate Amyl ether Formic acid PhenolAcetic acid Methylethyl ether Propionic acid Methyl acetate Aniscl Ethylacetate Pyran Propyi acetate Tri-tetra and penta- Amyl acetate methyleneoxides and the halogenated, preferably chlorinated, derivatives of theabove, as for example beta beta d'iighloroethyl ether (Chlorex),chloroacetic acid, e

While complexes of boron fluoride and oxygenated organic compounds as aclass are effective solvents for desulfurizing hydrocarbons, they areall not equal in their effectiveness and selectivity since the degree ofselectivity and effectiveness may vary with different complexes, thecomposition of the material being desulfurized and the conditions ofextraction.

The complexes suitable for the herein-described invention are liquid orsolids which melt slightly above room temperature, e. g. about F toabout F.

The boron fluoride complex is readily prepared by bubbling an excess ofboron fluoride through the oxygenated organic compound at about 50-150F. until a stoichiometric amount has been absorbed and then subjectingthe mixture to reduced pressure to remove the excess boron pounds. Thequantity of excess boron fluoride used with the complex may vary from atrace to a sufllcient amount to give a partial pressure of 600 lbs. ormore per square inch, and preferably at least 15 pounds per square inch.While complexes of BF3 with aliphatic or aromatic oxygenated compoundscan be used, we prefer to employ complexes of BF; with an oxygenatedalkane compound selected from the class consisting of others, esters andacids having not more than about 5, and preferably 2 carbon atoms in thealkyl group, and the halogen, preferably chlorine, derivatives thereof.

Specific examples of organic oxygenated comfluoride. In some cases itmay be desirable to carry out the BF: stripping at reduced temperaturesin order to avoid decomposition of the complex. The residual product isa complex of a mo] to moi ratio of boron fluoride to the oxygengatedorganic compound. The required amount of excess boron fluoride to beused in conjunction with the complex can then be added thereto. Al-

ternatively, an excess of the boron fluoride can be bubbled through theoxygenated organic com-' pound to form a mixture of the complex andexcess boron fluoride.

The choice of any particular oxygenated organic compounds used informing the boron fluoride complex wiildepend upon the feed to betreated with due consideration being given to the boiling point of thecomplex in relation to the boiling range of the feed material and theextract to be obtained therefrom. For example, the boron fluoride-methylether or boron fluorideethyl ether complexes boil at relatively lowtemperatures, namely 258 to 262 F. Therefore, if the extracted materialboils in this temperature range, it is preferable to use a higherboiling complex, for example, th adduct of boron fluoride with ahalogenated methyl or ethyl ether. Of course, under some conditionscomplexes having a boiling point lower than that of the extractedmaterial may be used in which case the complex can be recovered bydistilling or flashing oil the same from th extract.

The extraction can be carried out over a wide temperature range of about50 F. to about 150 F. or hi her, and referably from about 70 F. to about100 F. The quantity of complex used should be sufficient to give asatisfactory diphasic separation, and depending upon the materialextracted can vary from volumes percent to about 100 volumes percent ormore, and preferably from about volumes percent to about 50 volumespercent, based on the volume of hydrocarbon feed. although in some casesas little as 2 or 3 percent or less will give a satisfactory diphasicseparation. A pressure sufllcient to keep the materials in a liquidphase should be maintained in the extractor. In the extraction ofheavier stocks, such as for example lubricating stocks. im roved selectiity can be attained under certain conditions by the addition to theextraction mixture of an inert paraflin hydrocarbon diluent, such as forexample pentane, hexane or heptane.

The following procedure of desulfurizing a sulfur-bearing petroleum oilby extraction with a boron fluoride ethyl ether complex is given by wayof il ustration only and is not intended to be a limitation of ourinvention. Referring to Figure 1, a sulfur-bearing furnace oildistillate is introduced through a line III into the bottom portion' ofan extractor II, together with a small amount of boron fluoride passedfrom storage tank 22 through lines and 2i. The mixture is contactedcountercurrently with a boron fluoride-ethyl ether complex introducedinto the upper portion of extractor I I through line I 2. The extractoris suitably a packed tower, although other known suitable means ofobtaining intimate contact can be employed. The rafiinate is removedoverhead from the extractor II through a line I 3 and is introduced intoa sett er I 4 wherein any carryover of the complex, BF; mixture issettled out and returned to the extractor II through a line I5. Therailinite', substantially free of carryover complex and BF: is withdrawnfrom the settler it through line I8 and is introduced into thebottomportion of stripper I! which is provided with suitable heatingmeans, such as a heating coil I8. Any free boron fluoride is taken of!overhead through line I9 and either recycled to the extractor II throughlines 20 and I8, or taken 01! through line 2I to boron fluoride storagetank 22. The bottoms from the stripper I1 are removed through line 23and introduced into a fractionating system 24 equipped with suitableheating means such as heating coils 25. A substantially sulfur-freefurnace oil is recoveredas a product through line 28. The boron fluoridecomplex overhead is withdrawn from system 24 through line 21 and ispassed to complex storage tank 28. In the event some heavier productsare formed in the fractionating system 24. they are preferably withdrawnas bottoms and the substan'tially sulfur-free furnace oil is withdrawnas a side out (not shown).

The extract from extractor I I comprising the boron fluoride ethyl ethercomplex containing excess boron fluoride and the sulfur compoundsremoved from the furnace oil distillate, are withdrawn through line 28and introduced into a fractionating system 38 equipped with suitableheating means, such as heating coils 8|. The complex and BF: are removedoverhead through line 32 and either passed to the complex storage tank28 through line 33 or recycled to the extractor II through lines 88, 85and I2. Excess BF: is removed from complex storage 28 through line 3141which leads to BF: storage 22. Bottoms from the fractionator 88comprising sulfur compounds substantially free of boron fluoride ethylether complex and boron fluoride are removed therefrom through line 88.Although we have described the sulfur extract as a bottom drawoifmaterial, it will be readily understood that under certain conditionsthe sulfur compounds therein may be degraded to lower boiling materialin which case such lower boiling material may be withdrawn as a. sidedrawoil' stream (not shown).

Make-up boron fluoride can be introduced into the complex storage tank28 through line 3'! while make-up ether can be introduced into storagetank 28 from ether storage tank 38 through line I 39. If desired, excessboron fluoride can be introduced into the system from storage 22 throughlines 31, 40, 35 and I2.

The foregoing example illustrates the method of carrying out theherein-described invention in which boron fluoride complex is notdecomposed by distillation. However, certain boron fluoride complexesare unstable and decomposed upon distillation into boron fluoride andtheoxygenated organic compound. When employing such complexes they cannotbe recovered as in the hereinbefore described method. The followingexample illustrates one method of carrying out our invention employingboron fluoride complex 'which is decomposable under distillationconditions. For the purpose of illustration, the following procedureprovides a method for carrying out the invention employing as thesolvent a complex of boron fluoride with beta beta dichloroethyl ether(hereinafter referred to as the boron fluoride-Chlorex complex)containing an excess of boron fluoride.

Referring to Figure 2, the feed to be extracted, containing BF; fromstorage tank I22 and line I22a, is introduced through line IIO into thebottom portion of extraction tower III and countercurrently contactedwith a boron fluoride-Chlorex vcomplex from tank I I2 introduced intothe upper portion of the tower I'II through .line II2a. A temperature ofabout 40 to F. is maintained in the extraction tower Iii. The rafllnatefrom the extraction tower III is removed overhead through line II! to asettler I, wherein any entrained BFs-chlorex complex and BFE: is settledout and recycled to tower III through lines I I5 and I I8 or may bepassed through lines II! and ill to a complex recovery unit hereinafterdescribed. The raflinite from the settler I I4 is passed through line II8 to a BF: stripper I I8 provided with suitable heating means such as aheating coil-I28, wherein any small amount of dissolved BFa-Chlorexcomplex is decomposed by heating and the BF: from the complex together Awith the excess free through line I2I to a boron fluoride storage I22,or all or apart thereof may be recycled to tower III through lines I2Iaand I22a. The bottoms from the stripper II! are withdrawn through lineI23 to stripper I24. provided with suitable heating means such asheating coil I25, wherein theChlorex is taken overhead through line I tothe Chlorex storage I21. The raflinate, freed of boron fluoride andChlorex, is removed from B1": are removed overhead amass; 4 I a.

of boron fluoride, boronfluoride-ethyl ether complex and boronfluoride-ethyl ether plus boron fluoride respectively, for thirtyminutes at 70 to 74 F. and settling for thirty minutes. Experis mentNumbers 1, 2 and 3, and likewise 5, 6, .7 and 8 represent series ofsuccessive treats of a given charge. Experiment 4 represents a, singletreat. In these series treats 50 cubic centimeters of oil were withdrawnafter each treat for sulfur del0 termination.

TABLE I the tower I24 through line I28. If a light hydrocarbon diluenthas been used it may be removed as an overhead stream from the top ofthe stripper I24 and the Chlorex taken ofl as a higher boiling sidestream. Obviously, in the event the ramnate product has a lower boilingpoint than the Chlorex. the rafllnate will be taken overhead f'romstripper I24 and the Chlorex will be withdrawn from stripper I24 as abottom product and passed .to the Chlorex storage.

, The-extract from the extractor tower III comprising BFa-Chlorexcomplex, free BFa, and the extracted material from the feed is removedfrom p the tower III through line I29 and introduced into a stripper I30provided with suitable heating means such as heating coil I3I formaintaining a bottom temperature of'180" If. to 400 F. in the stripper.Boron fluoride-Chlorex complex and.

BF: from the settler II 4 may be introduced into the stripper I30through lines I" and I29. Boron fluoride is taken overhead from stripperI30 through lines I 3IIa-and I32 and passed to the boron fluoridestorage I22. If desired, all or a part of the BF: from stripper I30 canbe recycled to extractor. III through lines I 30a, I 32a and H0. Bottomsfrom the stripper I30 are withdrawn through line I 33 to stripper I 34provided with suitable heating means such as heating coils I35, whereinthe separation is made between the extracted sulfur compounds and theChlorex. Chlorex from the stripper I34 is taken overhead through lineI36 and passed to the Chlorex storage I2'I. The extracted sulfurcompounds are withdrawnfrom the stripper I34 through line I31.

The BFa-Chlorex complex can be formed in tank H2 by introducing properamounts of Chlorex and BF: from storage tanks I21 and I22 respectivelyinto tank II2 through lines I38 and I3! respectively and line I40. Toprevent excessive temperatures due to the heat of reaction between theBF: and Chlorex, the tank I22 should The synergistic effect of thecombination of the boron fluoride-ethyl ether complex plus an excess ofboron fluoride is well illustrated by the above data. Thus, comparingExperiment 5 with 1 and 4, when 150 cubic centimeters of the complex and34 grams of boron fluoride were used together the desulfurizationobtained was 11.4% higher than the sum of the two experiments using theconstituents separately; and comparing Experiment 6 with 2 and 4, whenusing 150 cubic centimeters of the complex and 55 gramsv of boronfluoride together, the desulfurization obtained was 12% higher than thesum of the two experiments using the constituents separately. The boronfluoride complex plus excess boron fluoride has the furtheradvantageover boron fluoride alone of markedly reduced operating pressures. Asshown in Table I,

the presence of the complex eiiects a reduc-' tion from 190 to 75 p. s.i. in operation with 55 g. BF: (Experiments 2 and 6). The word Chlorexused herein and in the accompanying drawings is beta beta dichloroethylether.

While we have described our invention by reference to certain specificembodiments thereof, the invention is not intended to be limited theretobut includes within the scope such modifications and variations as comewithin the appended claims.

We claim:

1. The method of desulfurizing a sulfur-bearing hydrocarbon materialcomprising extracting said hydrocarbon material at a temperature withinthe range of from about F. to about 00 150 F. with a solvent comprisingessentially a. complex of boron fluoride with an oxygenated alkanecompound having not more than about 2. The method of desulfurizing asulfur-bear ing hydrocarbon mixture comprising contacting said mixtureat a temperature within the range of from about 50 F. to about 150 F.with a solvent comprising essentially a, complex of boron fluoride withan oxygenated alkane compound having not more than about 5 carbon atomsin the alkyl group and an excess of boron fluoride said solvent beingused in an amount sumcient to give a diphasic separation.

guess:

3. The method of desulfuriaing a sulfur-bearing hydrocarbon comprisingcontactim said hydrocarbon at a temperature within the range of fromabout 50 F. to about 150 1". with a solvent comprising essentially acomplex of boron fluoride with an oxygenated alkanc compound having notmore than about carbon atoms in the alkyl group and an excess of boronfluoride. suflicient to give a partial pressure of at least pounds persquare inch said solvent being employed in amount suflicient to give adiphasic separation.

4. The method of desulfurizing a sulfur-bearing hydrocarbon comprisingcontacting said bydrocarbon at a temperature within the range of fromabout 50 F. to about 150' 1". with a solvent comprising essentially acomplex of boron fluoride with an alkane ester and an excess of boronfluoride said solvent being employed in amount suiflcient to give adiphasic separation.

5. Themethod ofclaim4inwhichthealkane ester is an alkane acetate havingnot more than about 5 carbon atoms in the alkyl group.

6. The method of claim 5 in which the alkane ester is ethyl acetate.

'1. The method of desulfurizing a sulfur-bearing hydrocarbon comprisingextracting said hydrocarbon with a composition comprising essentially acomplex of boron fluoride with an alkane ether having not more thanabout 5 carbon atoms in the alkyl group and an excess of boron fluoridesuflicient to give a partial pressure of from about 15 to about 600pounds per square inch.

8. The method of claim 7 in which the slime ether is an ethyl ether.

9'. The method of claim 8 in which the ethyl ether is beta betadichloroethyl ether.

10. The method of desulfurizing a sulfur-bearing hydrocarbon compoundcomprising extracting said compound at a temperature within the range offrom about 50 1". to about 150 l". with a solvent comprising essentiallya complex of boronfluoridewithanalk aneacidhavingnotmorethanscarbonatomsinthealkylgroupand an excess of boron fluoridesumcient to give a partialpressureofatieastaboutlSpoundsper square inchsaid solvent being employed in amount sumcient to effect a diphasicseparation.

11. The method of desulfurizing a hydrocarbon 011 comprising contactingsaid hydrocarbon oil at a temperature of from about F. to about 1". witha solvent comprising essentially a complex of boron fluoride with anoxygenated alkane compound having not more than about 5 carbon atoms inthe alkyl group and an excess of boron fluoride suflicient to give apartial pressure of at least about 15 pounds per square inch, saidsolvent bein employed in amount sufllcient to eiIect a diphasicseparation, separating a rafllnate fraction comprising said hydrocarbonoil having a sulfur content less than that of the original feed stockand a small amount of said complex and free boron fluoride, and anextract fraction comprising essentially said complex and free boronfluoride and sulfur compounds extracted from said hydrocarbon oil, andremoving said complex and free boron fluoride from the raflinate andextract fractions.

ARTHUR 1?. LEN. BERNARD L. EVERING.

REFERENCES CITED The following references are of record in the flle ofthis patent:

UNITED STATES PATENTS Number Name Date 2,343,841 Burk Mar. 7, 19442,375,675 Matuszak May 8, 1945 2,378,762 Prey June 19, 1945 2,415,171Horeczy Feb. 4, 1947 2,416,465 Axe Feb. 25, 194'!

1. THE METHOD OF DESULFURIZING A SULFUR-BEARING HYDROCARBON MATERIALCOMPRISING EXTRACTING SAID HYDROCARBON MATERIAL AT A TEMPERATURE WITHINTHE RANGE OF FROM ABOUT 50*F. TO ABOUT 150*F. WITH A SOLVENT COMPRISINGESSENTIALLY A COMPLEX OF BORON FLUORIDE WITH AN OXYGENATED ALKANECOMPOUND HAVING NOT MORE THAN ABOUT 5 CARBON ATOMS IN THE ALKYL GROUPAND AN EXCESS OF BORON FLUORIDE SAID SOLVENT BEING USED IN AN AMOUNTSUFFICIENT TO GIVE A DIPHASIC SEPARATION.